Is a husband sinful for preventing his wife from completing her university studies (Bachelor of Engineering) after he had promised her that before marriage, and that is out of a desire to protect her from temptations?

The conditions agreed upon by the spouses at the time of the marriage contract are binding, and the most deserving of fulfillment among conditions are those by which intimate relations become lawful. Therefore, if the wife stipulated completing her studies at the time of the contract, the husband must fulfill this condition, and he is not permitted to prevent her, due to the Almighty's saying: (O YOU WHO HAVE BELIEVED, FULFILL [YOUR] CONTRACTS). The husband's breach of the condition incurs sin and grants the wife the right to seek annulment of the marriage. However, if the condition involves committing something forbidden (haram), the husband is not obliged to fulfill it, due to the Prophet's (peace be upon him) saying: (Whoever stipulates a condition that is not in the Book of Allah: it is not binding on him, even if he stipulates a hundred conditions). The husband can communicate with his wife and persuade her regarding what he deems appropriate.